Two executives of the San Marcos company supplying portable restrooms to San Diego County pleaded guilty last year to illegally disposing tons of wastewater, and county officials continued to use the firm’s services after the criminal conviction.

A third official at Diamond Environmental Services was convicted of lying about when he learned about the scheme, which according to prosecutors saved the company millions of dollars by dumping the waste into city sewer systems across Southern California.

Owner Arie Eric De Jong III pleaded guilty to conspiracy to unlawfully discharge pollutants. Chief Operating Officer Warren Van Dam admitted similar charges and compliance manager Ronald Fabor was found guilty by a federal jury of two counts of perjury for lying to a grand jury.

“I’d rather not comment on how it happened because we still have an open case, but we are in compliance as of August 2016, two days after we were notified that we were not in compliance,” De Jong said by telephone this week.

The company — retained by San Diego County in 2015 — was convicted of dumping waste from portable toilets into municipal sewer systems in San Diego, San Marcos, Fullerton, Perris and Huntington Park rather than paying fees to dispose of the waste in specially designated facilities.

The unlawful dumpings saved the company up to $4.1 million between 2012 and 2016, prosecutors said, although DeJong disputed that assertion.

Last fall, county officials used an existing contract to order 13 portable restrooms in Lakeside, Spring Valley and on county property within the city of San Diego as part of its response to the hepatitis A crisis that killed 20 people and sickened almost 600 others last year.

The contract requires Diamond Environmental Services to comply with “all applicable federal, state, county and local laws, rules and regulations” and allows county officials to cancel the contract for failing to meet required terms.

It also calls on the company to comply with all environmental laws, hazardous materials rules and health and safety regulations.

County spokesman Michael Workman said in an email that the county issued a “cure notice” after becoming aware of the criminal case and requested additional information from the vendor.

“Based on their response and our review of the facts involved in this case, there was no proof that any violations were related to any county service contracts, therefore, no further action was deemed appropriate at that time.” he wrote. “The county continues to monitor their performance under our specific contract requirements, as well as any new information that may arise under this case.”

Workman said the county learned of the violations through news reports last June, then contacted the company to see about the violations. He said a satisfactory response was provided within days and the case was subsequently closed.

The county contract was signed in 2015 and pays Diamond Environmental Services $20,000 a year to provide the equipment, which is billed separately on a monthly basis.

The county’s 13 portable restrooms were the subject of a U-T Watchdog report Monday raising questions about the $500,000-plus the county has spent on security guards to protect the temporary toilets in recent months.

All three men are scheduled to be sentenced in federal court on Feb. 12.

CAPTION

As a sexual-misconduct case deepens within the San Diego Sheriff’s Department -- a 10th women has come forward with a legal claim against the county -- three alleged victims are raising questions about why the accused lawman has not been arrested.

As a sexual-misconduct case deepens within the San Diego Sheriff’s Department -- a 10th women has come forward with a legal claim against the county -- three alleged victims are raising questions about why the accused lawman has not been arrested.

CAPTION

The City of San Diego helped build a $2-million public restroom, after years of rejecting calls for toilets to address unsanitary conditions downtown.

The City of San Diego helped build a $2-million public restroom, after years of rejecting calls for toilets to address unsanitary conditions downtown.